The Western Ghats are a mountain range that runs almost parallel to the western coast of the Indian peninsula, located entirely in India. It is a UNESCOWorld Heritage Site and is one of the eight "hottest hotspots" of biological diversity in the world.[1][2] It is sometimes called the Great Escarpment of India.[3] The range runs north to south along the western edge of the Deccan Plateau, and separates the plateau from a narrow coastal plain, called Konkan, along the Arabian Sea. A total of thirty nine properties including national parks, wildlife sanctuaries and reserve forests were designated as world heritage sites - twenty in Kerala, ten in Karnataka, five in Tamil Nadu and four in Maharashtra.[4][5]

The area is one of the world's ten "Hottest biodiversity hotspots" and has over 7,400 species of flowering plants, 139 mammal species, 508 bird species, 179 amphibian species and 288 freshwater fish species; it is likely that many undiscovered species live in the Western Ghats. At least 325 globally threatened species occur in the Western Ghats.[8][9][10]

Western Ghats is one of the 33 recognised ecologically sensitive zones in the World. India has four such sensitive zones. They are the Western Ghats, the Eastern Himalayas, the Himalayan Range between Kashmir and Uttar Pradesh and the Andaman Islands. The Andamans along with the islands of Malaysia are an important sensitive zone. The significance of the Western Ghats is that along with its rich biodiversity, it also supports a rich environment-dependant civilisation of several thousand years.

The Western Ghats are the mountainous faulted and eroded edge of the Deccan Plateau. Geologic evidence indicates that they were formed during the break-up of the supercontinent of Gondwana some 150 million years ago. Geophysical evidence indicates that the west coast of India came into being somewhere around 100 to 80 mya after it broke away from Madagascar. After the break-up, the western coast of India would have appeared as an abrupt cliff some 1,000 m (3,300 ft) in elevation.[11]

The Western Ghats extend from the Satpura Range in the north, go south past Maharashtra, Goa, through Karnataka and into Kerala and Tamil Nadu. Major gaps in the range are the Goa Gap, between the Maharashtra and Karnataka sections, and the Palghat Gap on the Tamil Nadu and Kerala border between the Nilgiri Hills and the Anaimalai Hills.

The mountains intercept the rain-bearing westerly monsoon winds, and are consequently an area of high rainfall, particularly on their western side. The dense forests also contribute to the precipitation of the area by acting as a substrate for condensation of moist rising orographic winds from the sea, and releasing much of the moisture back into the air via transpiration, allowing it to later condense and fall again as rain.

The Western Ghats have several manmade lakes and reservoirs. The well known lakes are the Ooty (2500 m altitude, 34.0 ha) in Nilgiris, and the Kodaikanal (2285 m, 26 ha) and the Berijam in the Palani Hills. The Pookode lake of Wayanad in Kerala at Lakkadi is a beautiful scenic one with boating and garden arrangements. Most of the bigger lakes are situated in the state of Tamil Nadu. Two smaller lakes, the Devikulam (6.0 ha) and the Letchmi Elephant (2.0 ha) are in the Munnar range.

The majority of streams draining the Western Ghats are joining the rivers Krishna and Kaveri carry water during monsoon months only and have been dammed for hydroelectric and irrigation purposes. The major reservoirs are: Lonavala and Walwahn in Maharashtra; V.V. Sagar, K.R. Sagar, Bhadra reservoir at lakkavalli,linganamakki reservoir in the Malenadu area of Karnataka; Mettur Dam, Upper Bhavani, Mukurthi, Parson's Valley, Porthumund, Avalanche, Emerald, Pykara, Sandynulla, Karaiyar, Servalar, Kodaiyar, Manimuthar Dam and Glenmorgan in Tamil Nadu; and Kundallay and Maddupatty in the High Range of Kerala. Of these the Lonavla, Walwahn, Upper Bhavani, Mukurthi, Parson's Valley, Porthumund, Avalanche, Emerald, Pykara, Sandynulla, Glenmorgan, Kundally and Madupatty are important for their commercial and sport fisheries for rainbow trout (introduced), mahseer (native) and common carp (introduced).[17]

Fast running rivers and steep slopes have provided sites for many large hydro-electric projects. There are about 50 major dams along the length of the Western Ghats with the earliest project up in 1900 near Khopoli in Maharashtra.[18] Most notable of these projects are the Koyna Hydroelectric Project in Maharashtra, the Parambikulam Dam in Kerala, and the Linganmakki Dam in Karnataka.[12] The reservoir behind the Koyna Dam, the Shivajisagar Lake, has a length of 50 km(31 mi) and depth of 80 m(262 ft).[19] It is the largest hydroelectric project in Maharashtra, generating 1,920 MW of electric power.[20] Another major hydro electric project is Idukki dam in Kerala. This dam is one of the biggest in Asia and generates around 70% of power for Kerala state. Mullaperiyar dam near Thekkady is one of the oldest in the world and a major tourist attractions in Kerala. Water from this dam is drawn to the vast coastal plain of Tamil Nadu, forming a delta and making it rich in vegetation.

The Jog Falls in Karnataka, one of the most spectacular waterfalls in India

[[File:Mangalore-Bangalore highway [NH 48] in Karnataka runs through the Western Ghats]] During the monsoon season, numerous streams fed by incessant rain drain off the mountain sides leading to numerous and often spectacular waterfalls. Among the most well known is the Jog Falls, Kunchikal Falls, Dudhsagar Falls, Sivasamudram Falls, and Unchalli Falls. The Jog Falls is the highest natural plunge waterfall in South Asia and is listed among the 1001 natural wonders of the world.[21]Talakaveri wildlife sanctuary is a critical watershed and the source of the river Kaveri. This region has dense evergreen and semi-evergreen vegetation, with shola-grassland in areas of higher elevation. The steep terrain of the area has resulted in scenic waterfalls along its many mountain streams. Sharavathi and Someshvara Wildlife sanctuaries in Shimoga district are the source of the Tungabhadra River system. The Netravathi river has also its origin at Western Ghats of India flowing westwards to join Arabian sea at Mangalore.

Climate in the Western Ghats varies with altitudinal gradation and distance from the equator. The climate is humid and tropical in the lower reaches tempered by the proximity to the sea. Elevations of 1,500 m(4,921 ft) and above in the north and 2,000 m(6,562 ft) and above in the south have a more temperate climate. Average annual temperature here are around 15 °C (60 °F). In some parts frost is common, and temperatures touch the freezing point during the winter months. Mean temperature range from 20 °C (68 °F) in the south to 24 °C (75 °F) in the north. It has also been observed that the coldest periods in the South Western Ghats coincide with the wettest.[22]

During the monsoon season between June and September, the unbroken Western Ghats chain acts as a barrier to the moisture laden clouds. The heavy, eastward-moving rain-bearing clouds are forced to rise and in the process deposit most of their rain on the windward side. Rainfall in this region averages 3,000–4,000 mm (120–160 in) with localised extremes touching 9,000 mm (350 in). The eastern region of the Western Ghats which lie in the rain shadow, receive far less rainfall averaging about 1,000 mm (40 in) bringing the average rainfall figure to 2,500 mm (150 in). Data from rainfall figures reveal that there is no relationship between the total amount of rain received and the spread of the area. Some areas to the north in Maharashtra while receiving heavier rainfall are followed by long dry spells, while regions closer to the equator receiving less annual rainfall, have rain spells lasting almost the entire year.[22]

The northern portion of the range is generally drier than the southern portion, and at lower elevations makes up the North Western Ghats moist deciduous forests ecoregion, with mostly deciduous forests made up predominantly of teak. Above 1,000 meters elevation are the cooler and wetter North Western Ghats montane rain forests, whose evergreen forests are characterised by trees of family Lauraceae.

Above 1,000 meters are the South Western Ghats montane rain forests, also cooler and wetter than the surrounding lowland forests, and dominated by evergreen trees, although some montane grasslands and stunted forests can be found at the highest elevations. The South Western Ghats montane rain forests are the most species-rich ecologic region in peninsular India; eighty percent of the flowering plant species of the entire Western Ghats range are found in this ecologic region.

Historically the Western Ghats were well-covered in dense forests that provided wild foods and natural habitats for native tribal people. Its inaccessibility made it difficult for people from the plains to cultivate the land and build settlements. After the arrival of the British in the area, large swathes of territory were cleared for agricultural plantations and timber. The forest in the Western Ghats has been severely fragmented due to human activities, especially clear felling for tea, coffee, and teak plantations during 1860 to 1950. Species that are rare, endemic and habitat specialists are more adversely affected and tend to be lost faster than other species. Complex and species rich habitats like the tropical rainforest are much more adversely affected than other habitats. [23]

The area is ecologically sensitive to development and was declared an ecological hotspot in 1988 through the efforts of ecologist Norman Myers. Though this area covers barely five percent of India's land, 27% of all species of higher plants in India (4,000 of 15,000 species) are found here. Almost 1,800 of these are endemic to the region. The range is home to at least 84 amphibian species, 16 bird species, seven mammals, and 1,600 flowering plants which are not found elsewhere in the world.

"The Western Ghats has to be made an "ecologically sensitive zone". It is as important as the ecological system of the Himalayas for protection of the environment and climate of the country. The Central government will not give sanction for mining and hydroelectric projects proposed by the State Governments of Maharashtra, Karnataka and Goa that will destroy the Western Ghats eco-system.’’[26]

In a letter dated 20 June 2009, Mr. Ramesh said,

“The (proposed) 200-MW Gundia hydel project of Karnataka Power Corporation in Hassan district would drown almost 1,900 acres (7.7 km2) of thick forest in the already endangered Western Ghats along with all its fauna. This is something that both Karnataka and our country can ill-afford." "Power generation should not happen at the cost of ecological security."

The Expert Appraisal Committee appointed by Union Government also said that the project should not be taken up.[27]

In August 2011, the Western Ghats Ecology Expert Panel (WGEEP) designated the entire Western Ghats as an Ecologically Sensitive Area (ESA) and, assigned three levels of Ecological Sensitivity to its different regions.[28]

The Western Ghats are home to thousands of animal species including at least 325 globally threatened species. Many are endemic species, especially in the amphibian, reptilian and fish classes. Thirty two threatened species of mammals live in the Western Ghats. Of the 16 endemic mammals, 13 are threatened.[32]

The largest population of India's tigers outside the Sundarbans is in the forests where the boundaries of Karnataka, Tamil Nadu and Kerala meet. The largest numbers and herds of vulnerablegaur are found here with the Bandipur National Park and Nagarhole together holding over five thousand Gaur.[36] To the west the forests of Kodagu hold sizeable populations of the endangered Nilgiri langur.

Birds – There are at least 508 bird species. Most of Karnataka's five hundred species of birds[49] are from the Western Ghats region.[50]Bhadra Wildlife Sanctuary is located at the northern end of the Malabar ranges and the southern tip of the Sahyadri ranges and bird species from both ranges can be seen here.

The Western Ghats is home to 174 species of odonates (107 dragonflies and 67 damselflies), including 69 endemics.[43] Most of the endemic odonate are closely associated with rivers and streams, while the non-endemics typically are generalists.[43]

Molluscs – Seasonal rainfall patterns of the Western Ghats necessitate a period of dormancy for its land snails, resulting in their high abundance and diversity including at least 258 species of gastropods from 57 genera and 24 families.[54]

A total of 77 species of freshwater molluscs (52 gastropods and 25 bivalves) have been recorded from the Western Ghats, but the actual number is likely higher.[43] This include 28 endemics. Among the threatened freshwater molluscs are the mussels Pseudomulleria dalyi, which is a Gondwanan relict, and the snail Cremnoconchus, which is restricted to the spray zone of waterfalls.[43] According to the IUCN, 4 species of freshwater molluscs are considered endangered and 3 are vulnerable. An additional 19 species are considered data deficients (their status is unclear at present).[43]

Of the 7,402 species of flowering plants occur in the Western Ghats, 5,588 species are native or indigenous and 376 are exotics naturalized and 1,438 species are cultivated or planted as ornamentals. Among the indigenous species, 2,253 species are endemic to India and of them, 1,273 species are exclusively confined to the Western Ghats. Apart from 593 confirmed subspecies and varieties; 66 species, 5 subspecies and 14 varieties of doubtful occurrence are also reported and therefore amounting 8,080 taxa of flowering plants.[55]

The Western Ghats Ecology Expert Panel, headed by ecologist Madhav Gadgil, was a committee appointed by the Union Ministry of Environment and Forests to assess the biodiversity and environmental issues of the Western Ghats spread across six states-Kerala, Tamil Nadu, Karnataka, Goa, Maharashtra and Gujarat. The panel which was set up on March 14, 2010, submitted its report to the government on August 31, 2011.[56]Gadgil Committee and its successor Kasturirangan Committee recommended suggestions to protect the Western Ghats. However, both of them ran into controversy and were not implemented. Gadgil report was criticised for being too environment-friendly and not in tune with the ground realities. The Kasturirangan Committee tried to balance development and environment, but was labelled as being anti-environmental.[57][58][59] Both reports had major methodological flaws that prevented objective assessment of ecologically sensitive areas (ESAs).[60]

^Mathew George and Binoy C.F., An Overview of Insect Diversity of Western Ghats with Special Reference to Kerala State, retrieved 24 July 2007. (Online version[dead link]). Brief summary of work so far carried out on the insect fauna of Western Ghats of Kerala